The present invention relates to a non-contact-type electronic card which records personal information requiring security with respect to prevention of such as forgery or alternation, or a personal certification card that is suitably applied to a sheet.
As an identification card (ID card) or a credit card, a magnetic card which records data by means of a conventional magnetic recording method has been commonly utilized. However, a magnetic card had problems of insufficient anti-tampering with data due to the ease of rewriting of the data, of insufficient protection of data due to environmental susceptibility of magnetic record and of insufficient memory capacity.
Therefore, an IC card including an IC-chip has become popular in recent years. An IC card exchanges data with external equipment by reading and writing, through an electric connection provided on the surface or a loop antenna in the card. An IC card is provided with larger memory capacity compared to a magnetic card and has been significantly improved also in security. Particularly, a noncontact-type IC card, which is provided with an antenna inside the card and without having an electric connection outside the card, is superior in security compared to a contact-type IC card which has an electric connection on the card surface, and has become to be utilized in such application as an IC card which highly requires secrecy and prevention of forgery or alternation.
As such an IC card, for example, there is known a card in which the first sheet material and the second sheet material are laminated sandwiching an adhesive and an IC module including an IC-chip and an antenna are sealed in the adhesive layer.
Since an IC card requires high security, durability of an IC card has become important in respect to prevention of forgery or alternation. Particularly, since an electric part such as an antenna for information exchange between an IC-chip and the outside are included inside the card, various attempts to assure durability thereof has been performed. However, in accordance with becoming popular in various applications, further high durability has been required. Owing to characteristics of a card that may be usually carried, strong durability is required against repeated bending such as in a pocket of trousers, dropping, or pressure by such as coins. To satisfy such requirements, improvement such as to provide a strong reinforcement structure in an IC-chip has been proposed.
However, although a limited improvement of durability was observed, there caused problems in that sufficient durability was not obtained in various situations, for example, in respect to such as durability against impact with rapid stress, repeated bending durability with repeated stress, and repeated localized load, resulting in a break of an IC-chip or a break of a card to make electric operation impossible.
The present invention has been made in view of these points, and the object is to provide an IC card having an improved bending strength and being able to protect an IC-chip.
To solve the above-described problems and to achieve the object, the invention has been constituted as follows.
The invention described in item 1 is an IC card, provided with a part including an IC module comprised of an IC-chip, a reinforcement structure adjacent to the IC-chip and an antenna at a predetermined position between two supports of the front-side and the backside facing to each other via an adhesive, characterized in that, when a radius of curvature R1 is applied to said IC card, a radius of curvature of an outermost layer of a card is R1′, a reinforcement structure adjacent to said IC-chip and said IC-chip have radiuses of curvature of R2 and R3 respectively, and R1<R1′<R2.Itoreq.R3.
According to the invention described in item 1, it is possible to improve bending strength of an IC card and to protect an IC-chip, by defining a radius of curvature of each of an outermost layer of a card, a reinforcement structure and an IC-chip.
The invention described in item 2 is the IC card described in item 1, characterized in that D1/T1 is not less than 0.001 and not more than 0.05, wherein D1 is a thickness of an adhesive between said reinforcement structure and said front-side support and T1 is the maximum length of said reinforcement structure. It may be preferable that D1/T1 is 0.002 to 0.04.
According to the invention described in item 2, it is possible to improve bending strength of an IC card and to protect an IC-chip, by defining a relation between a thickness of an adhesive between a reinforcement structure and a front-side support and the maximum length of a reinforcement structure.
The invention described in item 3 is an IC card described in item 1, characterized in that said reinforcement structure is a metal reinforcement plate being adhered adjacent to said IC-chip, of which an area is larger than that of an IC-chip, and 0.02<tan .theta.<0.2, wherein .theta. is a degree between a plane, connecting the upper edge of a metal reinforcement plate and the upper edge of an IC-chip plane, and a horizontal plane of the metal reinforcement plate. It may be preferable that 0.03<tan .theta.<0.15.
According to the invention described in item 3, it is possible to improve bending strength of an IC card and to protect an IC-chip, by making 0.02<tan .theta.<0.2, wherein .theta. is a degree between a plane, connecting the upper edge of a metal reinforcement plate and the upper edge of an IC-chip plane, and a horizontal plane of the metal reinforcement plate.
The invention described in item 4 is an IC card described in item 1, characterized in that D2/T1 is not less than 0.001 and not more than 0.05, wherein D2 is a thickness of an adhesive between said IC-chip and said front-side support and T1 is the maximum length of said reinforcement structure. It may be preferable that D2/T1 is 0.002 to 0.04.
According to the invention described in item 4, it is possible to improve bending strength of an IC card and to protect an IC-chip, by defining the relation between a thickness of an adhesive between an IC-chip and a front-side support and the maximum length of a reinforcement structure.
The invention described in item 5 is an IC card described in any one of items 1 to 4, characterized in that a 2% modulus of elasticity of an adhesive adjacent to said IC-chip and said reinforcement structure is not less than 5 kg/mm.sup.2 and not more than 55 kg/mm.sup.2, and that a ductility at a breaking point is not less than 200% and not more than 1300%. It may be preferable that the 2% modulus of elasticity is 6 kg/mm.sup.2 to 50 kg/mm.sup.2. Further, it may be preferable that the reinforcing structural member has a Young's modulus of 150 Gpa to 450 Gpa.
According to the invention described in item 5, it is possible to improve bending strength of an IC card and to protect an IC-chip, by defining a 2% modulus of elasticity of an adhesive adjacent to an IC-chip and a reinforcement structure, and a ductility at a breaking point.
The invention described in item 6 is an IC card described in any one of items 1 to 4, characterized in that a thickness of said IC-chip is not less than 5 .mu.m and not more than 100 .mu.m.
According to the invention described in item 6, it is possible to improve bending strength of an IC card and to protect an IC-chip, by defining a thickness of an IC-chip.
The invention described in item 7 is an IC card described in any one of items 1 to 6, characterized in that an image receiving layer is provided on at least one of supports of the front-side and of the backside facing to each other, and that personal identification information comprised of a name and a face image is provided on the image receiving layer and a writable writing layer is provided on the other side.
According to the invention described in item 7, said IC card can be utilized as a personal certification card preferably applied in a non-contact type electronic card or sheet which has an image receiving layer and a writing layer and memorizes personal information requiring security such as prevention of forgery and alteration.
The invention described in item 8 is an IC card described in any one of items 1 to 7, characterized in that said adhesive is a reactive-type hot-melt adhesive.
According to the invention described in item 8, it is possible to relax stress and to obtain high durability due to an adhesive being a reactive-type hot-melt adhesive.